The use of thermoplastic polymers for many industrial applications is gaining increased acceptance today because of their excellent physical properties. For example, polycarbonates, especially aromatic polycarbonates formed from dihydric phenols, exhibit excellent physical attributes such as tensile strength, impact strength, and thermal stability. However, most polymers are generally deficient in at least one of several properties which curtails their use in certain products. For example, the use of polycarbonates in some applications, e.g., automotive, is limited somewhat because of their poor resistance to various organic solvents and other chemicals. On the other hand, materials such as the polyamides do not generally exhibit the superior physical properties of polycarbonates, but do exhibit excellent chemical resistance. It is thus apparent that a blend of several thermoplastic materials might result in a product possessing the best of each of their individual physical properties.
A particularly promising set of physical properties might result from the combination of the polycarbonates and polyamides discussed above. Blends of polycarbonates and various polyamides have been prepared in the past. For example, Japanese Kokai No. 116541/50 discloses a blend containing 80-95% by weight polycarbonate and 5-20% by weight of nylon 12. Furthermore, Japanese Patent Publication No. 26936/76 discloses adhesive compositions containing 5-40% by weight of a polycarbonate and 60-95% of a polyamide. Moreover, thermoplastic blends containing a polycarbonate and a polyamide along with a conjugated diene rubber copolymer are disclosed in U.S. Pat. No. 4,317,891.
While the polycarbonate/polyamide blends of the prior art may be suitable for some end uses, they generally exhibit serious disadvantages. For example, when molded, they often become severely laminated. Such undesirable lamination is often accompanied by poor impact strength. Furthermore, amine end groups of the polyamide react with carbonate bonds and thereby degrade the polycarbonate portion of the blend, resulting in loss of tensile strength, heat resistance and other desirable characteristics. It is thus readily apparent that the inherent chemical incompatibility between polycarbonates and polyamides results in blends of such materials having properties which are unacceptable for many uses.
It is therefore an object of the present invention to provide improved blends of polymeric materials which overcome the foregoing disadvantages.
It is another object of the present invention to provide a functionalized polycarbonate which is capable of chemical reaction with a polyamide.
It is a yet another object of the present invention to provide a compatible blend of a polycarbonate and a polyamide.
It is a further object to provide a copolymer of a polyamide and a carbonate polymer, and to provide a method for preparing such a copolymer.
It is still another object of the present invention to provide a method for preparing a compatible blend of a polycarbonate and a polyamide which may be molded into parts having excellent tensile strength, impact strength, and chemical resistance.